Improvement in converting non-chilling



UNITED STATES P T NT OFFICE,

SAMUEL A. FORD, OF ALLEGHENY, PENNSYLVANIA.

INlPROVEMENT lN CONVERTING NON-CHILLlNGlRON lNTO CHlLLlNG-IRON.

Specification forming part of Letters Patent No. 202,530, dated April16, 1878; application filed December 26, 1877;

To all whom it may concern:

Be it known that I, SAMUEL A. FoRD, of Allegheny, in the county ofAllegheny and State of Pennsylvania, have invented a new and usefulImprovement in Process of Treating Non-Chilling Irons and LightChilling-Irons; and 1 do hereby declare the following to be a full,clear, and exact description thereof.

My invention relates to the conversion of non-chilling into chillingirons; and consists in submitting a charge of melted non-chilling ironto the action of an air-blast for a few moments only--say from one tosix minutesthe air-blast being out off either just before or just afterthe appearance of the carbon-flame, according to the depth of chillrequired in the product.

In the manufacture of pig metal two processes are commonly followed inthe blast-furnace-the one known as the cold-blast and the other as thehot-blast process, and the products are known in the trade as hot-blastiron and cold-blast iron.

The cold-blast iron is low in silicon, and is especially adapted forchill-castings, &c. but its production is limited by the nature of theore required and the small size of furnaces it is practicable to work toadvantage. The hotblast iron, on the contrary, can be produced in anyquantities desired, as there is practically no limitation either inquality of ore or size of furnace; but the hot-blast iron is high insilicon, and, though well adapted for the Bessemer process, is anon-chillin g iron, totally unfit for the manufacture of chill-castings.

five to forty dollars per ton, while the hot-blast,

non-chilling iron can be procured at from seventeen to twenty dollarsper ton.

The main object of the present invention is to utilize the comparativelycheap hot-blast iron in the manufacture of chill-rolls, car-wheels,chill plows, malleable castings, and under all similar-circumstanceswhere the more expensive coal-blast charcoal chilling-irons are nownecessarily used; but the process is equally applicable to the treatmentof light chilling-irons where it is desirable to increase the depth ofthe chill.

I will now proceed to describe my invention, so that others skilled inthe art to which it appertains may apply the same.

Having melted the desired quantity of pig iron in a cupola or othersuitable furnace, or, if convenient, taking such a charge of molten irondirectly from the blast-furnace, I introduce it into a furnace, where itcan be treated by an air-blast. For this purpose I prefer a Bessemerconverter, wherein I submit the molten metal to the action of theair-blast for a few moments, shutting off the blast either just beforeor just after the appearance of the carbon-flame,varyin g the timeslightly, according to the quality of the metal and the depth of chillrequired.

If only a small amount of chill is required, I out off the blast justbefore the carbon of the metal begins to oxidize, which point can bedetermined by the increased strength of the flame with absence of thebrilliant yellow color. When a deep chill is desired, the blow. iscontinued until the brilliant yellow due to the oxidation of the carbonappears in the flame; but it is cut off before the disappearance of thesilicon-flame, or that flame which is seen at the commencement of theblow. The blow, having been carried to the extent indicated according tothe desired chill, is then cut off, and the metal poured into a ladle orother suitable vessel, and thence directly into chill-molds, or intosand-molds for the formation of castings, or into pigs, which can besubsequently remelted in a cupola or other suitable furnace for themanufacture of chillcastings. The whole process will usually occupy aspace of time varying from one to five min utes; but under somecircumstances it may be necessary to continue the blow somewhat longer,especially if the hot-blast iron composing the charge be extremely highin silicon.

The metal thus treated has not lost the qualities of cast-iron, but willbe found to have acquired the properties of the cold-blast charcoalchilling-irons. It will be found to be very hard, of great strength,and, if cast in a chill-mold, will when broken, show long white crystalstapering into gray metal. When cast in sand-molds, if the chillingproperty is not too great, it will exhibit a dark-gray color andclosegrain resembling cold -blast charcoaliron but if the chilling propertyis very high, then the edges of the casting will be slightly chilled andthe center of the piece of lightgray color. 7

Having thus described my invention, What I claim, and desire to secureby Letters Patent, is-- The method herein described for convertingnon-chilling irons into chilling-irons, and for increasing the chillingcapacity in light chilling-iron, which consists in subjecting a chargeof the melted metalto the action of an airblast for a limited time only,the blow being cut off either immediately before or immediately afterthe appearance of the carbon-flame, and before the disappearance of thesiliconflame, substantially as specified.

In testimony whereof 1, the said SAMUEL A. FORD, have hereunto set myhand.

SAMUEL A. Fonn.

Witnesses:

JAMES I. KAY, F. W. BITTER, Jr.

